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SPRING FLOOD OUTLOOK
NATIONAL WEATHER SERVICE
MISSOURI BASIN RIVER FORECAST CENTER
PLEASANT HILL, MO
FEB 14, 2018
NARRATIVE PART 1 OF 1
ATTN WFO`S SERVED BY MBRFC.
This Outlook is not for public release until Wednesday, February 14,
2018.
This Spring Outlook is for the Missouri River drainage which includes
rivers in Montana, Wyoming, Colorado, North and South Dakota,
Nebraska, Kansas, Iowa, Minnesota, and Missouri.
SPRING FLOOD OUTLOOK
Generally speaking, flood risk this Spring across the Missouri River
basin can be categorized as being below normal. There are some areas
which have a normal risk for flooding, and other areas which have a
higher than normal risk for flooding. However overall, the basin has
a reduced risk of flooding for the 2018 Spring flood season when
compared to historic normals.
A normal risk indicates that a location that typically experiences
Spring time flooding may flood again this year. A normal risk for
flooding does not necessarily mean that a location will flood,
however. For those locations which do not typically experience
flooding, a normal risk simply indicates that flooding is again not
expected this year.
Snowpack in the St. Mary and Milk River basins, the Upper Missouri
River basin above Ft. Peck, and the Yellowstone River basin, is
above normal. Headwaters of the North Platte River have a slightly
below normal snowpack, while those of the South Platte River have
a below normal snowpack. Widespread significant flooding in the
mountainous west is not likely this year due to mountain snowmelt
alone. Minor flooding is projected along the Clarks Fork Yellowstone
River in Montana. The Wind River in Wyoming could possibly see minor
flooding as well.
Plains snowpack is widespread, but generally shallow. Exceptions
being eastern Montana, and the area of northeastern Nebraska and
northwestern Iowa. For now, plains snowpack is not expected to be
a significant player in overall Spring flood potential.
Soils across the plains are reported to be deeply frozen. However,
given the dry Fall and early Winter, it is likely the soil, while
frozen, remains permeable to snow melt and Springtime rains.
Therefore, the frozen ground conditions currently existing across
the entire basin are not expected to exacerbate runoff production.
According to the latest Drought Monitor, 68% percent of the
Missouri River basin is abnormally dry, or worse. Thirty-one
percent of the basin is classified as being in drought. However,
even with these dry conditions, given the current and potential
plains snow, coupled with typical Springtime thunderstorm activity,
flooding is projected to occur this season, especially in the eastern
and southeastern portions of the basin.
Minor flooding is expected in the Big Sioux River basin in South
Dakota and Iowa. The Little Sioux River in Iowa is also projected
to see minor flooding.
Minor flooding is also possible along the lower reach of the North
Platte River in Nebraska. Some of the smaller tributaries in
extreme eastern Nebraska are also likely to experience minor
flooding this year.
Stranger Creek and the southern portion of the Big Blue River basin
in Kansas are likely to experience moderate, and minor flooding,
respectively. The Marias des Cygnes-Osage basin in eastern Kansas
and south-central Missouri will also see moderate level flooding
this year.
The Grand, Osage, and Tarkio River basins in Missouri are likely to
have moderate flooding this year. The Platte River, and many of the
smaller tributaries to the Missouri River in the State of Missouri
are projected to experience minor flooding this Spring and early
Summer. The Missouri River itself is projected to experience minor
flooding in the reach downstream of Nebraska City, due to isolated
rounds of convective activity. Again, this is not atypical.
Freeze-up ice jam flooding has already been reported at many
locations this winter. However impacts have been relatively minor
and localized in extent. High water due to ice formation has been
reported along reaches of the Wind River in Wyoming, the North Platte
and South Platte Rivers in Nebraska, the Niobrara River in Nebraska,
and the Gallatin and Missouri Rivers in Montana. Break-up ice jam
flooding is expected to be somewhat widespread this season, but
projecting locations and severity is difficult at best.
These projections of river stages are based on current observed
states of streamflow, soil moisture, and snowpack, coupled with
future precipitation and temperature patterns and anticipated
operational hydrologic changes such as reservoir releases and canal
diversions. "Outlooks" are provided for long-range (weeks to months)
projections based on climatological patterns of precipitation and
temperature. "Forecasts" are provided for short-term (days)
projections based on forecast patterns of precipitation and
temperature. The uncertainty of these products varies from
season to season and location to location. The uncertainty of
forecasts tend be less than the uncertainty of outlooks due to
their shorter lead time.
Users of these products are encouraged to contact their nearest
National Weather Service Forecast Office for continued updates of
meteorological conditions which can have significant impacts on
flood preparedness planning and flood fighting activities.
For additional quantitative information please refer to AHPS products
for probabilistic outlooks of potential flooding. Refer to flood
forecasts and products, if any are currently issued, for information
about ongoing or near-term anticipated flooding.
The next Spring Outlook is scheduled for release on February 28th.
Additional river information, including the monthly Water Supply
Outlook, can be accessed at the following URL:
http://weather.gov/mbrfc
Current Snow Conditions
The conditions listed below are based on observations and model
data as of Wednesday morning, February 14th.
Montana Plains
Recent heavy snow across the central plains of Montana has snow
depths in the 15-25 inch range, with maximum water equivalents
ranging from 2-4 inches. In the far eastern plains of Montana,
snow depths are generally less than 15 inches with water equivalents
of less than 2 inches.
Wyoming and Colorado Plains
There is very little snow being reported in the plains of Wyoming
and Colorado. Snow depths are less than 3 inches with water
equivalents less than half an inch.
Mountainous West
Snowpack conditions in the mountainous areas of the basin vary from
one watershed to another. In Montana, the Jefferson, Musselshell,
Missouri headwaters, Sun, Teton, Marais, St. Mary, and Milk River
basins are reporting an above normal snowpack (120-150%). In Wyoming,
the Tongue, Bighorn, Powder, Wind, and Yellowstone River basins are
also reporting an above normal snowpack (120-150%). The higher
elevations of the North Platte River basin are reporting a near to
slightly below average snowpack (80-100%). In Colorado, the higher
elevations of the South Platte River basin are reporting a below
average snowpack (60-80%).
North Dakota
North Dakota has snow depths ranging from 2-8 inches with water
equivalents generally less than 1 inch.
South Dakota
Snow depths of 5-10 inches with water equivalents in the 1-2 inch
range are being reported across the northwestern corner and
southeastern corner of South Dakota. The Black Hills are reporting
15-25 inches of snow depth with water equivalents in the 3-5 inch
range. The rest of South Dakota is reporting less than 5 inches
of snow depth with water equivalents of less than 1 inch.
Iowa
Snow depths of 5-10 inches are being reported across northwestern
Iowa with water equivalents in the 1-2 inch range. Snow depths
were generally less than 5 inches across southwestern Iowa with
water equivalents less than 1 inch.
Nebraska
Much of Nebraska is reporting 1-3 inches of snow depth with water
equivalents of less than half an inch. Higher amounts across the
northeastern corner of the state ranged from 5-8 inches with water
equivalents in the 1-2 inch range.
Missouri and Kansas
Little or no snow is being reported across Missouri and Kansas.
Current Soil Moisture Conditions
A large portion of the Missouri River basin is experiencing drought
conditions. The US Drought Monitor indicates moderate to severe
drought conditions across much of the western Dakotas, eastern
Montana, southern Colorado, southern Kansas, and eastern Missouri.
Abnormally dry conditions are indicated across the eastern Dakotas,
southern Nebraska, northern Kansas, western Missouri, and southern
Iowa. The remainder of the basin has near normal soil conditions.
Isolated frost depth reports suggest that soils across Montana and
North Dakota have frost penetration ranging from 2-4 feet. Frost
depth reports across Wyoming, South Dakota, Nebraska, and Iowa range
from 1-2 feet. Frost depths of less than 1 foot are being reported
across Colorado, Kansas, and Missouri.
Current River Conditions
The majority of the rivers in the northern two-thirds of the basin are
iced over. Generally, river levels in this portion of the basin are
currently running near to above normal, or estimated to be so if the
rivers are frozen. In the southern third of the basin, rivers have
flow conditions that are near to below historical medians.
A summary of river flow conditions at selected river stations for
February 14th follows:
Long Term Current
Mean (CFS) (CFS)
James River - Huron, SD 63 68 (EST)
Big Sioux River - Akron, IA 177 707 (EST)
Platte River - Louisville, NE 6600 10700 (EST)
Kansas River - Desoto, KS 2580 2490
Gasconade River - Jerome, MO 1610 528
Missouri River - Omaha, NE 19500 27100
Missouri River - Rulo, NE 25500 29200
Missouri River - St. Joseph, MO 27700 31300
Missouri River - Waverly, MO 33000 35400
Missouri River - Hermann, MO 52700 38800
END MBRFC
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